The subject invention is directed toward the art of pipe and tube joints and couplings and, more particularly, to an improved flange type joint.
The invention is especially suited for forming connecting joints in critical processing systems where fluid entrapment or retention within the system must be avoided. In such systems, it is often difficult to eliminate recesses or pockets that retain process fluid between system runs or when switching fluids in a common line.
The problem of recesses and fluid trapping pockets is especially prevalent with respect to connecting joints which rely on resilient, elastomeric seals and packings. The typical prior packed joint was often difficult to assemble and frequently resulted in undesired discontinuities between the connected sections. Consequently, the need has existed for a joint construction which is easy to assemble and which does not produce pockets, recesses, or undesirable discontinuities which can trap process fluids.
In packed joints of the type under consideration, the components must generally be axially driven together under relatively high force to produce the necessary sealing pressures. Also, the joints are typically used in systems where frequent disassembly for cleaning, maintenance, and/or system changeover.
To meet the high force and rapid disassembly requirements, it has been the practice to use circumferentially extending, multi-section clamping rings. The rings sections have internal wedge surfaces that act against corresponding wedge surfaces on the exterior of the joint to drive the joint components axially together. Actuation of the clamp ring is generally accomplished by a thumb screw which pulls the sections together.
While generally satisfactory, problems have been encountered with the clamp rings. For example, in systems subject to substantial vibration, loosening of the clamp ring and loss of sealing force has occurred. Additionally, the repeated high force tightening and releasing of the thumb screws has produced significant galling and erosion of the nose of the thumb screws and/or the engaged portion of the clamp rings. This makes it difficult to retighten the clamps and also generates metal particles which are often highly undesirable in the system environment.